“I want to have the best restaurant in the country. I want to obtain that third Michelin star.”

If it isn’t clear chef Curtis Duffy wants to be uttered in the same breath as Thomas Keller, Daniel Boulud, and his former boss Grant Achatz, this removes all doubt: In what might be the most significant departure of a chef since Achatz left Trio to open Alinea, the Tribune has learned that Duffy will be leaving two Michelin-starred Avenues in the Peninsula Hotel to head his own restaurant.

Duffy’s restaurant will be in the West Loop, which in recent years has become fine dining’s “it” neighborhood (Blackbird, Girl & The Goat and Next are all within a 10-minute walk). He’s aiming for a spring 2012 opening.

The as-yet-unnamed restaurant, Duffy said, aims for “food that will be more refined. We’re going to pull back just a bit and push forward at the same time. We want to have a bit more control with the food, and push forward in terms of flavor combination.”

Duffy became chef de cuisine at Avenues in April 2008 after Graham Elliot Bowles left to open his eponymous restaurant. Six months later, Tribune restaurant critic Phil Vettel handed Duffy four stars. Before that, he was the opening chef de cuisine at Alinea under Achatz, who he met while working at Trio. Duffy, a Columbus, Ohio native, is also an alumnus of Charlie Trotter’s.

It’s been a banner year for Duffy, 36, who was shortlisted for the James Beard Award for Best Regional Chef in May, a Jean Banchet Award winner in January, and last November, awarded two stars in Chicago’s inaugural Michelin Guide.

“It’s been an amazing year. We just want to continue that path. And it’ll be so much sweeter underneath my name.”